package com.gitee.weixin.redis;

import java.util.Collections;

import redis.clients.jedis.Jedis;

public class RedisTool {
	private static final String	LOCK_SUCCESS			= "OK";
	private static final String	SET_IF_NOT_EXIST		= "NX";
	private static final String	SET_WITH_EXPIRE_TIME	= "PX";
	private static final Long	RELEASE_SUCCESS			= 1L;

	/**
	 * 尝试获取分布式锁
	 * 
	 * @param jedis
	 *            Redis客户端
	 * @param lockKey
	 *            锁
	 * @param requestId
	 *            请求标识
	 * @param expireTime
	 *            超期时间
	 * @return 是否获取成功
	 */
	public static boolean tryGetDistributedLock(Jedis jedis, String lockKey, String requestId, int expireTime) {

		String result = jedis.set(lockKey, requestId, SET_IF_NOT_EXIST, SET_WITH_EXPIRE_TIME, expireTime);

		if (LOCK_SUCCESS.equals(result)) {
			return true;
		}
		return false;

	}

	/**
	 * 释放分布式锁
	 * 
	 * @param jedis
	 *            Redis客户端
	 * @param lockKey
	 *            锁
	 * @param requestId
	 *            请求标识
	 * @return 是否释放成功
	 */
	public static boolean releaseDistributedLock(Jedis jedis, String lockKey, String requestId) {

		String script = "if redis.call('get', KEYS[1]) == ARGV[1] then return redis.call('del', KEYS[1]) else return 0 end";
		Object result = jedis.eval(script, Collections.singletonList(lockKey), Collections.singletonList(requestId));

		if (RELEASE_SUCCESS.equals(result)) {
			return true;
		}
		return false;

	}
}
